Chris Kelly, a former Facebook executive and 2010 Democratic candidate for attorney general, is bankrolling a November ballot measure that would stiffen penalties in California for human traffickers and create new requirements for sex offenders.

Proposition 35, whose opponents have no formal organization or funding, would increase prison sentences for traffickers from five to eight years to 12 years to life, depending on the circumstances. It raises the maximum fines from $100,000 to $1.5 million and requires that the money be spent to help trafficking victims and to assist law enforcement agencies prevent trafficking and rescue victims.

Under Prop. 35, all traffickers would have to register as sex offenders, and all registered sex offenders in the state, whether their convictions are for trafficking or other offenses, would have to disclose their Internet providers and online identities to law enforcement agencies. The measure also mandates new training for law enforcement officers.

Kelly has contributed $1.86 million to the campaign, about 85 percent of total donations to the campaign, according to an analysis of campaign donations by MapLight, a nonpartisan organization in Berkeley that studies money and politics.

He said he was inspired to join the cause as a result of his work at Facebook and because so much trafficking occurs online. Instead of facilitating trafficking, he said, the Internet should play a role in fighting it.

Kelly said Prop. 35 would send a signal to traffickers that their crimes, which often victimize women and children, will not be tolerated and that the harsher penalties would dissuade some potential traffickers.

"It provides a greater incentive for prosecutors to bring cases," he said. "Is it going to end trafficking tomorrow? Of course not."

Supporters of the measure have been working to inform voters that California has a major trafficking problem. In 2003, for example, the FBI identified San Francisco, San Diego and Los Angeles as three of the nation's 13 high-intensity child-prostitution areas. Last year, Shared Hope International, an organization that supports victims, gave California an F for its laws on child-sex trafficking.

There are critics of the measure, even though they have not formed a committee or raised money. The American Civil Liberties Union of Northern California has opposed the measure because of its requirement that all sex offenders provide law enforcement with information about their online activity.

"This provision essentially eliminates the ability of registrants to engage in anonymous online speech and imposes a substantial burden whenever a registrant wants to use a new online platform to speech, infringing on registrants' First Amendment right to free speech," the civil liberties group wrote.

Maxine Doogan, a prostitute and founder of the Erotic Service Providers Legal, Educational and Research Project, said Prop. 35 could subject prostitutes to trafficking accusations even if they enter the field on their own volition. She said prostitutes are already afraid to report when they are assaulted and the initiative would make it worse.

She acknowledged that it is not easy to oppose a measure meant to protect the victims of trafficking.

"We are out there alone," Doogan said. "We don't have any money. We can't get the attention of anybody. Nobody is really caring about us."

Kelly said opponents' concerns were not justified. He said he hopes that voters will not only approve the California measure this fall, but that other states will pursue similar laws.

Barry Krisberg, a criminal justice expert at UC Berkeley's law school, said the increased penalties for traffickers could drive the problem further underground, when what is needed is more aid for victims.

"This just escalates penalties," he said. "We've tried that for years, and it doesn't do any good."

Still, he said, "It may well pass because it sounds good. Everybody's against sex trafficking."

Proposition 35

What it would do: Increase prison sentences and fines for human traffickers; mandate that all traffickers register as sex offenders and that all sex offenders in the state provide law enforcement agencies with information about their online activity; require trafficking training for law enforcement officers.

Who's for it: Former Democratic attorney general candidate and Facebook executive Chris Kelly has contributed $1.86 million to the campaign, the vast majority of its funding. The measure has racked up a long list of endorsers, including the state Republican and Democratic Parties.

Who's against it: Opponents have raised no money or formed a committee to fight Prop. 35. The American Civil Liberties Union of Northern California and the Erotic Service Providers Legal, Educational and Research Project have opposed it.